Communication systems rely upon a wireless or wired transmission medium for exchanging communications between endpoints. Information transmitted across the transmission medium may be subject to impairments, and accordingly may not be correctly received or may not be received at all. Various techniques are employed to ensure that transmitted information is correctly received, including error correction encoding, power control, packet retransmission, and the like.
One technique that employs a combination of error correction encoding and packet retransmission is known as hybrid automatic retransmission request (HARQ). HARQ involves a combination of forward error correction encoding (FEC) and automatic retransmission requests (ARQ) such that an endpoint sends either an acknowledgement (ACK) or negative acknowledgment (NACK) for each received packet. When a NACK is transmitted, the original packet is FEC encoded and retransmitted to the endpoint. The endpoint attempts to recover the original packet information by using a combination of the original packet and the retransmitted packet.